Display device and method for driving same

ABSTRACT

A pixel circuit of a display device includes an electro-optical element, a drive transistor, a first transistor including a first conduction terminal connected to an anode terminal of the electro-optical element, a second conduction terminal to which an initialization voltage is applied, and a gate terminal connected to a scanning line, a second transistor including a first conduction terminal connected to a gate terminal of the drive transistor and a gate terminal connected to an immediately preceding scanning line selected in a horizontal interval immediately before the scanning line is selected, and a third transistor being diode-connected and including a drain terminal and a gate terminal to which an initialization voltage is applied and a source terminal connected to a second conduction terminal of the second transistor. Thus, a display device that can suppress both the bright spots and the black floating is provided.

TECHNICAL FIELD

The disclosure relates to a display device, and more particularly, to adisplay device including a pixel circuit including an electro-opticalelement.

BACKGROUND ART

Organic Electro Luminescence (hereinafter referred to as “EL”) displaydevices including pixel circuits including organic EL elements haverecently been coming into practical use. The pixel circuit of theorganic EL display device includes a drive transistor, a writing controltransistor, and the like in addition to the organic EL element. A ThinFilm Transistor (hereinafter referred to as a TFT) is used in thesetransistors. The organic EL element is a kind of electro-optical elementand emits light at brightness according to the amount of flowingcurrent. The drive transistor is provided in series with the organic ELelement, and controls the amount of current flowing through the organicEL element.

Variation and fluctuation occur in characteristics of the organic ELelement and the drive transistor. Thus, variation and fluctuation incharacteristics of these elements need to be compensated in order toperform higher picture quality display in the organic EL display device.For the organic EL display device, a method for compensating thecharacteristics of the elements inside the pixel circuits and a methodfor compensating the characteristics of the elements outside the pixelcircuit are known. In the organic EL display device, processing ofinitializing a gate terminal of the drive transistor may be performedbefore a voltage (hereinafter referred to as a data voltage) accordingto an image signal is written to the pixel circuit.

For the organic EL display device, many pixel circuits have beenproposed. For example, the pixel circuit 95 including seven TFTs: M91 toM97 and an organic EL element L9 illustrated in FIG. 11 is known. TheTFT: M91 is turned on in a horizontal interval immediately before ahorizontal interval at which a data voltage is written to the pixelcircuit 95. At this time, a gate terminal of the TFT: M94 (drivetransistor) is initialized by using an initialization voltage Vini. TheTFT: M97 is turned on in a horizontal interval at which the data voltageis written to the pixel circuit 95. At this time, an anode terminal ofthe organic EL element L9 is initialized by using the initializationvoltage Vini. In addition, pixel circuits of an organic EL displaydevice having an initialization function are described in PTLS 1 and 2,for example.

CITATION LIST Patent Literature

PTL 1: JP 2016-109772 A

PTL 2: JP 2016-110055 A

SUMMARY Technical Problem

In the display device including the pixel circuit 95 illustrated in FIG.11 (hereinafter, referred to as a known display device), the gateterminal of the TFT: M94 and the anode terminal of the organic ELelement L9 are initialized by using the same initialization voltageVini. As a result, there is a problem in the known display device thatbright spots and black floating are prone to occur. Reasons for thiswill be described below.

In a case where the organic EL element L9 is turned off during the lightemission period of the organic EL element L9, a high data voltage toturn off the TFT: M94 is applied to the gate terminal of the TFT: M94.However, in a case where the initialization voltage Vini is low, adrain-source voltage of the TFT: M91 increases, and the leakage currentflowing through the TFT: M91 increases. Thus, the gate voltage of theTFT: M94 is reduced, and current flows through the TFT: M94, and theorganic EL element L9 emits light. As a result, the bright spots occurin a display screen.

FIG. 12 is a diagram showing a measurement result of brightness near thebright spots in the known display device. The brightness shown in FIG.12 is preferably always low. The actual brightness, however, is low atthe start of the light emission period, and then gradually increases.FIG. 12 shows a change in brightness in a case where the initializationvoltage Vini is a relatively low voltage V11 and a change in brightnessin a case where the initialization voltage Vini is a relatively highvoltage V12. The change in brightness is smaller in the latter. Thus, tosuppress the generation of the bright spots, the initialization voltageVini is preferably increased.

However, in a case where the initialization voltage Vini is increased,the voltage (Vini−ELVSS) applied to the organic EL element L9 during thenon-light emission period of the organic EL element L9 is increased, andmay exceed a light emission threshold voltage of the organic EL elementL9. As a result, a current flows through the organic EL element L9, andthe organic EL element L9 emits faint light. As a result, the blackfloating occurs in the display screen.

FIG. 13 is a diagram showing a measurement result of the brightness of apixel in a case where the black floating occurs in the known displaydevice. The brightness shown in FIG. 13 is also preferably always low.The actual brightness, however, is increased in the non-light emissionperiod (the period indicated by the dashed lines). FIG. 13 shows achange in brightness in a case where the initialization voltage Vini isfrom V21 to V24 (where V21<V22<V23<V24). The change in brightness issmaller as the initialization voltage Vini is lower. Thus, to suppressthe generation of the black floating, the initialization voltage Vini ispreferably lowered.

In this way, in the known display device, in a case where the generationof the bright spots is suppressed by increasing the initializationvoltage Vini, the black floating occurs, whereas in a case where thegeneration of the black floating is suppressed by lowering theinitialization voltage Vini, the bright spots occur. As a result,depending on the initialization voltage Vini, either the bright spots orthe black floating is prone to occur.

Thus, an object is to provide a display device that can suppress boththe bright spots and the black floating.

Solution to Problem

The above-described problem can be solved by a display device, forexample, including: a display portion including a plurality of scanninglines, a plurality of data lines, and a plurality of pixel circuitstwo-dimensionally arranged; a scanning line drive circuit configured todrive the plurality of scanning lines; and a data line drive circuitconfigured to drive the plurality of data lines, wherein each of theplurality of pixel circuits includes an electro-optical element providedon a path connecting a first conductive member and a second conductivemember for supplying a power supply voltage and configured to emit lightat brightness according to a current flowing through the path, a drivetransistor provided in series with the electro-optical element on thepath and configured to control the amount of current flowing through thepath, a first transistor including a first conduction terminal connectedto an anode terminal of the electro-optical element, a second conductionterminal to which an initialization voltage is applied, and a gateterminal connected to a scanning line of the plurality of scanninglines, a second transistor including a first conduction terminalconnected to a gate terminal of the drive transistor and a gate terminalconnected to an immediately preceding scanning line selected in ahorizontal interval immediately before the scanning line is selected,and a third transistor being diode-connected and including a drainterminal and a gate terminal to which the initialization voltage isapplied, and a source terminal connected to a second conduction terminalof the second transistor.

The above-described problem can also be solved by a method for driving adisplay device including the display portion described above, the methodincluding initializing the gate terminal of the drive transistor byturning on the second and third transistors, initializing the anodeterminal of the electro-optical element by turning on the firsttransistor, and applying a voltage according to an image signal to thegate terminal of the drive transistor by driving a scanning line of theplurality of scanning lines and a data line of the plurality of datalines.

Advantageous Effects of Disclosure

According to the display device and the driving method of the samedescribed above, both the bright spots and the black floating can besuppressed by initializing the gate terminal of the drive transistor andthe anode terminal of the electro-optical element to the differentvoltage levels. An increase in the layout area of the display portioncan be prevented, by initializing the gate terminal of the drivetransistor and the anode terminal of the electro-optical element byusing the same wiring line.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of a displaydevice according to a first embodiment.

FIG. 2 is a circuit diagram illustrating a pixel circuit of the displaydevice illustrated in FIG. 1.

FIG. 3 is a timing chart of the display device illustrated in FIG. 1.

FIG. 4A is a view for describing an action of the pixel circuitillustrated in FIG. 2.

FIG. 4B is a continuation of FIG. 4A.

FIG. 4C is a continuation of FIG. 4B.

FIG. 4D is a continuation of FIG. 4C.

FIG. 5 is a layout diagram illustrating a part of the pixel circuitillustrated in FIG. 2.

FIG. 6A is a cross-sectional view taken along line A-A′ of FIG. 5.

FIG. 6B is a cross-sectional view taken along line B-B′ of FIG. 5.

FIG. 7 is a block diagram illustrating a configuration of a displaydevice according to a second embodiment.

FIG. 8 is a circuit diagram illustrating a pixel circuit of the displaydevice illustrated in FIG. 7.

FIG. 9 is a timing chart of the display device illustrated in FIG. 7.

FIG. 10 is a circuit diagram of a pixel circuit of a display deviceaccording to a third embodiment.

FIG. 11 is a circuit diagram of a pixel circuit of a known displaydevice.

FIG. 12 is a diagram showing a measurement result of brightness near thebright spots in a known display device.

FIG. 13 is a diagram showing a measurement result of brightness of apixel in a case where the black floating occurs in a known displaydevice.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a display device according to each embodiment will bedescribed with reference to drawings. The display device according toeach embodiment is an organic EL display device including a pixelcircuit including an organic EL element. The organic EL element is akind of electro-optical element, and is also called an organic lightemitting diode or an OLED. In the following description, the horizontaldirection of the drawings is referred to as the row direction, and thevertical direction of the drawings is referred to as the columndirection. m and n represent integers greater than or equal to 2, irepresents an integer greater than or equal to 1 and less than or equalto m, and j represents an integer greater than or equal to 1 and lessthan or equal to n.

First Embodiment

FIG. 1 is a block diagram illustrating a configuration of a displaydevice according to a first embodiment. A display device 10 illustratedin FIG. 1 includes a display portion 11, a display control circuit 12, ascanning line drive/light emission control circuit 13, and a data linedrive circuit 14. The scanning line drive/light emission control circuit13 is a circuit combining a scanning line drive circuit with a lightemission control circuit.

The display portion 11 includes (m+1) scanning lines G0 to Gm, n datalines S1 to Sn, m light emission control lines E1 to Em, and (m×n) pixelcircuits 15. The scanning lines G0 to Gm extend in the row direction andare arranged parallel to each other. The data lines S1 to Sn extend inthe column direction and are arranged orthogonal to the scanning linesG0 to Gm and parallel to each other. The light emission control lines E1to Em extend in the row direction and are arranged parallel to thescanning lines G0 to Gm. The scanning lines G1 to Gm and the data linesS1 to Sn intersect at (m×n) locations. The (m×n) pixel circuits 15 areeach two-dimensionally arranged corresponding to each intersection pointbetween the scanning lines G1 to Gm and the data lines S1 to Sn. Thepixel circuit 15 in the i-th row and j-th column is connected to twoscanning lines Gi−1 and Gi, a data line Sj, and a light emission controlline Ei. Each of the plurality of pixel circuits 15 is constantlysupplied with voltages (a high-level power supply voltage ELVDD, alow-level power supply voltage ELVSS, and an initialization voltageVini) of three kinds by using a conductive member (a wiring line or anelectrode) (not illustrated).

The display control circuit 12 outputs a control signal CS1 to thescanning line drive/light emission control circuit 13, and outputs acontrol signal CS2 and an image signal VS to the data line drive circuit14. The scanning line drive/light emission control circuit 13 drives thescanning lines G0 to Gm and the light emission control lines E1 to Em onthe basis of the control signal CS1. The data line drive circuit 14drives the data lines S1 to Sn on the basis of the control signal CS2and the image signal VS. More specifically, the scanning linedrive/light emission control circuit 13 sequentially selects one of thescanning lines G0 to Gm on the basis of the control signal CS1 andapplies an active-level voltage (the low-level voltage) to the selectedscanning line. The n pixel circuits 15 connected to the selectedscanning line are collectively selected as a result. The data line drivecircuit 14 applies n data voltages according to the image signal VS tothe data lines S1 to Sn on the basis of the control signal CS2. n datavoltages are written to the selected n pixel circuits 15, respectively,as a result. The scanning line drive/light emission control circuit 13applies to the light emission control line Ei, a voltage (the high-levelvoltage) indicating the non-emitting in a period including a selectperiod of the pixel circuits 15 in the (i−1)-th row and the i-th row,and a voltage (the low-level voltage) indicating the light emission inthe other period. The organic EL element in the pixel circuit 15 in thei-th row emits light at a brightness according to the data voltagewritten to the pixel circuit 15 while the voltage of the light emissioncontrol line Ei is at the low-level.

FIG. 2 is a circuit diagram illustrating the pixel circuit 15. FIG. 2illustrates a pixel circuit 15 in the i-th row and j-th column. A pixelcircuit 15 illustrated in FIG. 2 includes eight TFTs: M11 to M18, anorganic EL element L1, and a capacitor C1. TFTs: M11 to M18 areP-channel transistors, and a TFT: M12 is a double gate transistor havingtwo gate terminals. Note that the TFT: M12 may be a single gatetransistor having one gate terminal. Hereinafter, a power source wiringline for the high-level power supply voltage ELVDD is referred to as afirst power source wiring line 16 and a power source wiring line for thelow-level power supply voltage ELVSS is referred to as a second powersource wiring line 17.

Note that, a TFT included in the pixel circuit 15 may be an amorphoussilicon transistor including a channel layer made of amorphous silicon,a low-temperature polysilicon transistor including a channel layer madeof low-temperature polysilicon, or an oxide semiconductor transistorincluding a channel layer formed of an oxide semiconductor. For example,Indium-Gallium-Zinc Oxide (referred to as IGZO) may be used as the oxidesemiconductor. A TFT included in the pixel circuit 15 may be a top gatetype or a bottom gate type. A pixel circuit including an N-channeltransistor may also be used instead of the pixel circuit 15 includingthe P-channel transistor. In a case of configuring the pixel circuitusing the N-channel transistor, the polarity of the signal and the powersupply voltage supplied to the pixel circuit may be reversed.

A source terminal of the TFT: M15 and one electrode (an upper electrodein FIG. 2) of the capacitor C1 are connected to the first power sourcewiring line 16. A first conduction terminal (a right terminal in FIG. 2)of the TFT: M13 is connected to the data line Sj. A drain terminal ofthe TFT: M15 and a second conduction terminal of the TFT: M13 areconnected to a source terminal of the TFT: M14. A drain terminal of theTFT: M14 is connected to a first conduction terminal of the TFT: M12 (alower terminal in FIG. 2) and a source terminal of the TFT: M16. A drainterminal of the TFT: M16 is connected to an anode terminal of theorganic EL element L1 and a source terminal of the TFT: M17. A cathodeterminal of the organic EL element L1 is connected to the second powersource wiring line 17. A second conduction terminal of the TFT: M12 isconnected to a gate terminal of the TFT: M14, the other electrode of thecapacitor C1, and a first conduction terminal (an upper terminal in FIG.2) of the TFT: M11. A second conduction terminal of the TFT: M11 isconnected to a source terminal of the TFT: M18. The initializationvoltage Vini is applied to drain terminals of the TFTs: M17, M18 and agate terminal of the TFT: M18. Gate terminals of the TFTs: M12, M13, andM17 are connected to the scanning line Gi, and gate terminals of theTFTs: M15 and M16 are connected to the light emission control line Ei.The gate terminal of the TFT: M11 is connected to an immediatelypreceding scanning line Gi−1 selected during a horizontal intervalbefore a period at which the scanning line Gi is selected. Since thedrain terminal and the gate terminal of the TFT: M18 are connected toeach other, the TFT: M18 is diode-connected.

In the pixel circuit 15, the organic EL element L1 is provided on a pathconnecting a first and a second conductive members (the first powersource wiring line 16 and the second power source wiring line 17) forsupplying a power supply voltage, and functions as an electro-opticalelement that emits light at brightness according to a current flowingthrough the path. The TFT: M14 is provided in series with theelectro-optical element on the path and functions as a drive transistorthat controls the amount of current flowing through the path. The TFT:M17 functions as a first transistor that includes a first conductionterminal connected to an anode terminal of the electro-optical element,a second conduction terminal to which the initialization voltage Vini isapplied, and a gate terminal connected to the scanning line Gi. The TFT:M11 functions as a second transistor that includes a first conductionterminal connected to a gate terminal of the drive transistor and a gateterminal connected to the immediately preceding scanning line Gi−1selected in a horizontal interval immediately before the scanning lineGi is selected. The TFT: M18 is diode-connected and functions as a thirdtransistor that includes a drain terminal and a gate terminal to whichan initialization voltage Vini is applied, and a source terminalconnected to a second conduction terminal of the second transistor.

The TFT: M13 functions as a writing control transistor that includes afirst conduction terminal connected to the data line Sj, a secondconduction terminal connected to a first conduction terminal of thedrive transistor, and a gate terminal connected to the scanning line Gi.The TFT: M12 functions as a threshold value compensation transistor thatincludes a first conduction terminal connected to a second conductionterminal of the drive transistor, a second conduction terminal connectedto the gate terminal of the drive transistor, and a gate terminalconnected to the scanning line Gi. The TFT: M15 functions as a firstlight emission control transistor that includes a first conductionterminal connected to the first conductive member, a second conductionterminal connected to the first conduction terminal of the drivetransistor, and a gate terminal connected to the light emission controlline Ei. The TFT: M16 functions as a second light emission controltransistor that includes a first conduction terminal connected to thesecond conduction terminal of the drive transistor, a second conductionterminal connected to the anode terminal of the electro-optical element,and a gate terminal connected to the light emission control line Ei. Thecapacitor C1 is provided between the first conductive member and thegate terminal of the drive transistor. The electro-optical elementincludes a cathode terminal connected to the second conductive member.

FIG. 3 is a timing chart of the display device 10. FIG. 3 illustrates achange in voltage in a case where a data voltage is written to the pixelcircuit 15 in the i-th row and j-th column. In FIG. 3, the periods Pa toPd are an emission stop period, a drive transistor initializationperiod, a write period, and a light emission period, respectively, ofthe pixel circuit 15 in the i-th row. In the write period, the thresholdvalue compensation for the TFT: M14 and the initialization of theorganic EL element L1 are also performed. The length of the period Pb isequal to the length of one horizontal interval. Hereinafter, signals onthe scanning lines Gi−1 and Gi are respectively referred to as scanningsignals Gi−1 and Gi, and a signal on the light emission control line Eiis referred to as a light emission control signal Ei.

FIGS. 4A to 4D are diagrams illustrating actions of the pixel circuit 15in the i-th row and j-th column in the periods Pa to Pd, respectively.FIGS. 4A to 4D describe voltages supplied from the outside of the pixelcircuit 15, voltages at nodes in the pixel circuit 15, and currentsflowing in the pixel circuit 15. Note that the voltages illustrated inthe diagrams are merely examples for facilitating the understanding ofthe actions of the pixel circuit 15. The voltages supplied from theoutside of the pixel circuit 15 and the voltages at the nodes in thepixel circuit 15 may be voltages other than that illustrated in thediagrams.

Before a time 11, the scanning signals Gi−1 and Gi are at thehigh-level, and the light emission control signal Ei is at thelow-level. Thus, the TFTs: M15 and M16 are in an on state, and the TFTs:M11 to M13, M17 and M18 are in an off state. At this time, in a casewhere a gate-source voltage of the TFT: M14 is less than or equal to athreshold voltage, a current flows from the first power source wiringline 16 toward the second power source wiring line 17 via the TFTs: M15,M14, and M16 and the organic EL element L1, and the organic EL elementL1 emits light at brightness according to the amount of the flowingcurrent.

At the time 11, the light emission control signal Ei is changed to thehigh-level. Accordingly, the TFTs: M15 and M16 are turned off. Thus, nocurrent flows via the organic EL element L1 at and after the time t11,and the organic EL element L1 is brought into a non-emitting state (FIG.4A).

Next, at a time t12, the scanning signal Gi−1 is changed to thelow-level. Accordingly, the TFT: M11 is turned on, and the TFT: M18 isalso turned on. Thus, the current Ia flows from the gate terminal of theTFT: M14 toward the wiring line applied with the initialization voltageVini via the TFTs: M11 and M18, and the gate terminal of the TFT: M14 isinitialized by using the initialization voltage Vini (FIG. 4B). Giventhat the threshold voltage of the TFT: M18 is VthA (<0), the gatevoltage of the TFT: M14 after the initialization is (Vini+|VthA|). Theinitialization voltage Vini is set at a lower level such that the TFT:M14 is turned on immediately after the scanning signal Gi is changed tothe low-level (immediately after a time t14).

Next, at a time t13, the scanning signal Gi−1 is changed to thehigh-level. Accordingly, the TFT: M11 is turned off, and the TFT: M18 isalso turned off. At the time t13, the initialization of the gateterminal of the TFT: M14 terminates.

Next, at the time t14, the scanning signal Gi is changed to thelow-level. Accordingly, the TFTs: M12, M13, and M17 are turned on. Atand after the time t14, the gate terminal and the drain terminal of theTFT: M14 are electrically connected to each other via the TFT: M12 in anon state, and thus the TFT: M14 is in a diode-connected state. Thus, acurrent Ib flows from the data line Sj toward the gate terminal of theTFT: M14 via the TFTs: M13, M14, and M12 (FIG. 4C). The gate voltage ofthe TFT: M14 increases due to the current Ib. In a case where agate-source voltage of the TFT: M14 is equal to a threshold voltage ofthe TFT: M14, the current Ib does not flow. Given that a thresholdvoltage of the TFT: M14 is VthB (<0) and a data voltage applied to thedata line Sj in a period from the time t14 to a time t15 is Vd, a gatevoltage of the TFT: M14 after a lapse of sufficient time from the timet14 is (Vd−|VthB|).

At and after the time t14, a current Ic flows from the anode terminal ofthe organic EL element L1 toward the wiring line applied with theinitialization voltage Vini via the TFT: M17, and the anode terminal ofthe organic EL element L1 is initialized by using the initializationvoltage Vini. The anode voltage of the organic EL element L1 after theinitialization is Vini.

Next, at the time t15, the scanning signal Gi is changed to thehigh-level. Accordingly, the TFTs: M12, M13, and M17 are turned off. Attime t15, initialization of the anode terminal of the organic EL elementL1 terminates. At and after the time t15, the capacitor C1 holds aninter-electrode voltage (ELVDD−Vd+|VthB|).

Next, the light emission control signal Ei is changed to the low-levelat a time t16. Accordingly, the TFTs: M15 and M16 are turned on. At andafter the time t16, a current Id flows from the first power sourcewiring line 16 toward the second power source wiring line 17 via theTFTs: M15, M14, M16 and the organic EL element L1 (FIG. 4D). Agate-source voltage Vgs of the TFT: M14 is held at (ELVDD−Vd+|VthB|) byaction of the capacitor C1. The current Id flowing at and after the timet16 is, therefore, given by Equation (1) below by using a constant K.

$\begin{matrix}\begin{matrix}{{Id} = {K\left( {{Vgs} - {{VthB}}} \right)}^{2}} \\{= {K\left( {{ELVDD} - {Vd} + {{VthB}} - {{VthB}}} \right)}^{2}} \\{= {K\left( {{ELVDD} - {Vd}} \right)}^{2}}\end{matrix} & (1)\end{matrix}$

In this way, at and after the time t16, the organic EL element L1 emitslight at brightness according to the data voltage Vd written to thepixel circuit 15 regardless of the threshold voltage VthB of the TFT:M14.

The anode-cathode voltage of the organic EL element L1 after theinitialization is (Vini−ELVSS). Given that a maximum value of the amountof variation of the anode voltage of the organic EL element L1 in thenon-light emission period of the organic EL element L1 is ΔV, and alight emission threshold voltage of the organic EL element L1 is Vem,the initialization voltage Vini and the low-level power supply voltageELVSS are determined to satisfy Relationship (2) below.Vini−ELVSS+ΔV<Vem  (2)

As a result, the organic EL element L1 is prevented from emitting faintlight in the non-light emission period of the organic EL element L1, andthe occurrence of the black floating can be prevented.

FIG. 5 is a layout diagram illustrating a part of the pixel circuit 15.FIG. 6A is a cross-sectional view taken along line A-A′ of FIG. 5, andFIG. 6B is a cross-sectional view taken along line B-B′ of FIG. 5. FIG.5 illustrates six wiring lines 41 to 46 and four contact holes 51 to 54.The wiring lines 41 and 42 are formed in a polysilicon wiring linelayer, the wiring lines 43 and 44 are formed in a first metal wiringline layer, the wiring line 45 is formed in a second metal wiring linelayer, and the wiring line 46 is formed in a third metal wiring linelayer. As illustrated in FIG. 6A and FIG. 6B, the pixel circuit 15 isformed by sequentially layering the wiring line of the polysiliconwiring line layer, the gate insulating film 62, the wiring line of thefirst metal wiring line layer, the insulating film 63, the wiring lineof the second metal wiring line layer, the insulating film 64, and thewiring line of the third metal wiring line layer in necessary positionson the substrate 61.

The contact hole 51 electrically connects the wiring line 45 formed inthe second metal wiring line layer and the wiring line 46 formed in thethird metal wiring line layer. The contact hole 52 electrically connectsthe wiring line 41 formed in the polysilicon wiring line layer and thewiring line 46 formed in the third metal wiring line layer. The contacthole 53 electrically connects the wiring line 44 formed in the firstmetal wiring line layer and the wiring line 46 formed in the third metalwiring line layer. The contact hole 54 electrically connects the wiringline 42 formed in the polysilicon wiring line layer and the wiring line46 formed in the third metal wiring line layer.

The wiring line 43 is the scanning line Gi−1, and the wiring line 45 isthe wiring line applied with the initialization voltage Vini. The X1portion illustrated in FIG. 5 is connected to the gate terminal of theTFT: M14, and the X2 portion illustrated in FIG. 5 is connected to ananode terminal of an organic EL element L1 included in the pixel circuit15 of an immediately upper row. The TFT: M11 is formed at a positionwhere the wiring line 41 and the wiring line 43 intersect each other.The TFT: M18 is formed at a position where the wiring line 41 and thewiring line 44 intersect each other. The TFT: M17 included in the pixelcircuit 15 of i−1 row (the pixel circuit 15 of an immediately upper row)is formed at a position where the wiring line 42 and the wiring line 43intersect each other. Note that FIG. 5, FIG. 6A, and FIG. 6B illustrateexamples of configurations of the TFTs included in the pixel circuit 15.The TFTs included in the pixel circuit 15 may have configurations otherthan that illustrated in FIG. 5, FIG. 6A, and FIG. 6B.

In the display device 10, the first conduction terminal of the TFT: M11is connected to the gate terminal of the TFT: M14 (the drivetransistor); the TFT: M18 is diode-connected, the drain terminal and thegate terminal of the TFT: M18 are applied with the initializationvoltage Vini, and the source terminal of the TFT: M18 is connected tothe second conduction terminal of the TFT: M11; and the gate terminal ofthe TFT: M11 is connected to the scanning line Gi−1. Thus, the TFTs: M11and M18 are turned on in a horizontal interval immediately before ahorizontal interval at which the pixel circuit 15 is written, and thegate terminal of the TFT: M14 is initialized by using the initializationvoltage Vini. The source terminal of the TFT: M17 is connected to theanode terminal of the organic EL element L1, the drain terminal of theTFT: M17 is applied with the initialization voltage Vini, and the gateterminal of the TFT: M17 is connected to the scanning line Gi. Thus, theTFT: M17 is turned on in the horizontal interval at which the pixelcircuit 15 is written, and the anode terminal of the organic EL elementL1 is initialized by using the initialization voltage Vini. In thedisplay device 10, the gate terminal of the TFT: M14 is initialized byturning on the TFTs: M11 and M18, the anode terminal of the organic ELelement L1 is initialized by turning on the TFT: M17, and the datavoltage according to the image signal VS is applied to the gate terminalof the TFT: M14 by driving the scanning line Gi and the data line Sj. Asa result, an image according to the image signal VS can be displayed.

In the display device 10, the gate voltage of the TFT: M14 after theinitialization is greater than the anode voltage of the organic ELelement L1 after the initialization. The gate voltage of the TFT: M14after the initialization is equal to the voltage (Vini+|VthA|) obtainedby adding the absolute value of the threshold voltage VthA of the TFT:M18 to the initialization voltage Vini, and the anode voltage of theorganic EL element L1 after the initialization is equal to theinitialization voltage Vini.

As described above, in the known display device including the pixelcircuit 95 illustrated in FIG. 11, the gate terminal of the drivetransistor (TFT: M94) and the anode terminal of the organic EL elementL9 are initialized to the same voltage level by using the initializationvoltage Vini. As a result, there is a problem in the known displaydevice that depending on the initialization voltage Vini, either thebright points or the black floating is prone to occur.

In contrast, in the display device 10 according to the presentembodiment, the gate voltage of the drive transistor (TFT: M14) isinitialized to (Vini+|VthA|), and the anode voltage of the organic ELelement L1 is initialized to Vini. In this way, the gate terminal of thedrive transistor and the anode terminal of the organic EL element L1 areinitialized to the different voltage levels. Thus, in a case where thethreshold voltage VthA of the TFT: M18 is appropriately determined, thegeneration of the bright spots can be prevented by increasing the gatevoltage of the TFT: M14 after the initialization, while the generationof the black floating can be prevented by lowering the anode voltage ofthe organic EL element L1 after the initialization.

As described above, according to the display device 10 according to thepresent embodiment, both the bright spots and the black floating can besuppressed by initializing the gate terminal of the drive transistor(TFT: M14) and the anode terminal of the electro-optical element(organic EL element L1) to the different voltage levels. The gateterminal of the drive transistor and the anode terminal of theelectro-optical element are initialized by using the same wiring line(the wiring line having the initialization voltage Vini), and this canprevent the layout area of the display portion 11 from increasing.

Second Embodiment

FIG. 7 is a block diagram illustrating a configuration of a displaydevice according to a second embodiment. A display device 20 illustratedin FIG. 7 includes a display portion 21, a display control circuit 12, ascanning line drive circuit 23, and a data line drive circuit 14. Thesame elements in the present embodiment as those in the first embodimentare denoted by the same reference signs, and the description thereofwill be omitted.

The display portion 21 includes (m+1) scanning lines G0 to Gm, n datalines S1 to Sn, and (m×n) pixel circuits 25. The scanning lines G0 toGm, the data lines S1 to Sn, and the (m×n) pixel circuits 25 arearranged in the same manner as the first embodiment. The pixel circuit25 in the i-th row and j-th column is connected to two scanning linesGi−1, Gi and a data line Sj. Similar to the first embodiment, each ofthe plurality of pixel circuits 25 is constantly supplied with thehigh-level power supply voltage ELVDD, the low-level power supplyvoltage ELVSS, and the initialization voltage Vini.

The scanning line drive circuit 23 drives the scanning lines G0 to Gm onthe basis of the control signal CS1. The scanning line drive circuit 23is a circuit in which the function of driving the light emission controllines E1 to Em is removed from the scanning line drive/light emissioncontrol circuit 13 according to the first embodiment.

FIG. 8 is a circuit diagram illustrating the pixel circuit 25. FIG. 8illustrates a pixel circuit 25 in the i-th row and j-th column. Thepixel circuit 25 illustrated in FIG. 8 includes seven TFTs: M21 to M27,an organic EL element L2, and a capacitor C2. The TFT: M24 is anN-channel transistor, and other TFTs are P-channel transistors.

A source terminal of the TFT: M21 and one electrode (an upper electrodein FIG. 8) of the capacitor C2 are connected to the first power sourcewiring line 16. A drain terminal of the TFT: M21 is connected to a drainterminal of the TFT: M24. A source terminal of the TFT: M24 is connectedto an anode terminal of the organic EL element L2 and a source terminalof the TFT: M26. A cathode terminal of the organic EL element L2 isconnected to the second power source wiring line 17. A first conductionterminal (a left terminal in FIG. 8) of the TFT: M23 is connected to thedata line Sj. A second conduction terminal of the TFT: M23 is connectedto a first conduction terminal (upper terminal in FIG. 8) of the TFT:M22. A gate terminal of the TFT: M21 is connected to the other electrodeof the capacitor C2, a gate terminal of the TFT: M22, a secondconduction terminal of the TFT: M22, and a first conduction terminal(upper terminal in FIG. 8) of the TFT: M25. A second conduction terminalof the TFT: M25 is connected to a source terminal of the TFT: M27. Theinitialization voltage Vini is applied to drain terminals of the TFTs:M26 and M27 and a gate terminal of the TFT: M27. Gate terminals of theTFTs: M23 and M26 are connected to the scanning line Gi. Gate terminalsof the TFTs: M24 and M25 are connected to an immediately precedingscanning line Gi−1 selected during a horizontal interval before thescanning line Gi is selected. Since a drain terminal and the gateterminal of the TFT: M22 are connected to each other, the TFT: M22 isdiode-connected. Since the drain terminal and the gate terminal of theTFT: M27 are connected to each other, the TFT: M27 is diode-connected.The TFT: M24 is turned on complementary to the TFT: M25.

In the pixel circuit 25, the organic EL element L2 is provided on a pathconnecting a first and a second conductive members (the first powersource wiring line 16 and the second power source wiring line 17) forsupplying a power supply voltage and functions as an electro-opticalelement that emits light at brightness according to a current flowingthrough the path. The TFT: M21 is provided in series with theelectro-optical element on the path and functions as a drive transistorthat controls the amount of current flowing through the path. The TFT:M26 functions as a first transistor that includes a first conductionterminal connected to the anode terminal of the electro-optical element,a second conduction terminal to which the initialization voltage Vini isapplied, and a gate terminal connected to the scanning line Gi. The TFT:M25 functions as a second transistor that includes a first conductionterminal connected to the gate terminal of the drive transistor and agate terminal connected to the immediately preceding scanning line Gi−1selected in a horizontal interval immediately before the scanning lineGi is selected. The TFT: M27 is diode-connected and functions as a thirdtransistor that includes a drain terminal and a gate terminal to whichthe initialization voltage Vini is applied and a source terminalconnected to a second conduction terminal of the second transistor.

The TFT: M23 functions as a writing control transistor that includes afirst conduction terminal connected to the data line Sj and the gateterminal connected to the scanning line Gi. The TFT: M22 functions as athreshold value compensation transistor that includes a first conductionterminal connected to a second conduction terminal of the writingcontrol transistor, and includes a second conduction terminal and a gateterminal connected to a gate terminal of the drive transistor. The TFT:M24 functions as a fourth transistor that includes a first conductionterminal connected to the anode terminal of the electro-optical element,a second conduction terminal connected to a second conduction terminalof the drive transistor, and is complementarily conducted to the secondtransistor. The capacitor C2 is provided between the first conductivemember and the gate terminal of the drive transistor. The firstconduction terminal of the drive transistor is connected to the firstconductive member, and a cathode terminal of the electro-optical elementis connected to the second conductive member.

FIG. 9 is a timing chart of the display device 20. FIG. 9 illustrates achange in voltage when a data voltage is written to the pixel circuit 25in the i-th row and j-th column. In FIG. 9, the period between times t21and t22 is the pre-charge period of the pixel circuit 25 in the i-throw. The period between times t23 and t24 is the write period of thepixel circuit 25 in the i-th row. The pixel circuit 25 in the i-th rowemits light in a period other than the pre-charge period.

Before the time t21, the scanning signals Gi−1 and Gi are at thehigh-level. Thus, the TFTs: M23, and M25 to M27 are in an off state, andthe TFT: M24 is in an on state. At this time, in a case where agate-source voltage of the TFT: M21 is less than or equal to a thresholdvoltage, a current flows from the first power source wiring line 16toward the second power source wiring line 17 via the TFTs: M21, M24 andthe organic EL element L2, and the organic EL element L2 emits light atbrightness according to the amount of the flowing current.

At a time t21, the scanning signal Gi−1 is changed to the low-level.Accordingly, the TFT: M24 is turned off, the TFT: M25 is turned on, andthe TFT: M27 is also turned on. Thus, at and after the time t21, sincethe TFT: M24 is turned off, no current flows via the organic EL elementL2, and the organic EL element L2 is brought into a non-emitting state.Since the TFTs: M25 and M27 are turned on, the gate terminal of the TFT:M21 is initialized by using the initialization voltage Vini. Given thatthe threshold voltage of the TFT: M21 is VthC (<0), a gate voltage ofthe TFT: M21 after the initialization is (Vini+|VthC|). Theinitialization voltage Vini is set at a lower level such that the TFT:M21 is turned on immediately after the scanning signal Gi is changed tothe low-level (immediately after the time t23).

Next, at the time t22, the scanning signal Gi−1 is changed to thehigh-level. Accordingly, the TFT: M24 is turned on, the TFT: M25 isturned off, and the TFT: M27 is also turned off. At the time t22, theinitialization of the gate terminal of the TFT: M21 terminates. Further,in a similar manner to the period before the time t21, in a case where agate-source voltage of the TFT: M21 is less than or equal to a thresholdvoltage, a current flows via the organic EL element L2, and the organicEL element L2 emits light.

Next, at the time t23, the scanning signal Gi is changed to thelow-level. Accordingly, the TFTs: M23 and M26 are turned on. Since theTFTs: M23 is turned on, a current flows from the data line Sj toward agate terminal of the TFT: M22 via the TFTs: M23 and M22. The gatevoltages of the TFTs: M21 and M22 rise due to this current. In a casewhere a gate-source voltage of the TFT: M22 is equal to a thresholdvoltage of the TFT: M22, no current flows. Given that a thresholdvoltage of the TFT: M21 is Vth1 (<0), a threshold voltage of the TFT:M22 is Vth2 (<0), and a data voltage applied to the data line Sj in aperiod from the time t23 to the time t24 is Vd, a gate voltage of theTFTs: M21 and M22 after a lapse of sufficient time from the time t23 is(Vd−|Vth2|). Since the TFT: M26 is turned on, the anode terminal of theorganic EL element L2 is initialized by using the initialization voltageVini. The anode voltage of the organic EL element L2 after theinitialization is Vini.

Next, at the time t24, the scanning signal Gi is changed to thehigh-level. Accordingly, the TFTs: M23 and M26 are turned off. At andafter the time t24, the capacitor C2 holds an inter-electrode voltage(ELVDD−Vd+|Vth2|). A current flows from the first power source wiringline 16 toward the second power source wiring line 17 via the TFTs: M21,M24 and the organic EL element L2. A gate-source voltage Vgs of the TFT:M21 is held at (ELVDD−Vd+|Vth2|) by action of the capacitor C2. Thecurrent Ie flowing at and after the time t24 is, therefore, given byEquation (3) below by using a constant K.

$\begin{matrix}\begin{matrix}{{Ie} = {K\left( {{Vgs} - {{{Vth}\; 1}}} \right)}^{2}} \\{= {K\left( {{ELVDD} - {Vd} + {{{Vth}\; 2}} - {{{Vth}\; 1}}} \right)}^{2}}\end{matrix} & (3)\end{matrix}$

In a case in which the threshold voltage Vth1 of the TFT: M21 and thethreshold voltage Vth2 of the TFT: M22 are equal, Equation (4) below isderived from Equation (3).Ie=K(ELVDD−Vd)²  (4)

In this way, at and after the time t24, the organic EL element L2 emitslight at brightness according to the data voltage Vd written to thepixel circuit 25 regardless of the threshold voltage Vth1 of the TFT:M21. In the display device 20 as well, similar to the first embodiment,the initialization voltage Vini and the low-level power supply voltageELVSS are determined to satisfy Relationship (2).

In the display device 20, the first conduction terminal of the TFT: M25is connected to the gate terminal of the TFT: M21 (drive transistor);the TFT: M27 is diode-connected, the drain terminal and the gateterminal of the TFT: M27 are applied with the initialization voltageVini, and the source terminal of the TFT: M27 is connected to a secondconduction terminal of the TFT: M25; and the gate terminal of the TFT:M25 is connected to the scanning line Gi−1. Thus, the TFTs: M25 and M27are turned on in a horizontal interval immediately before a horizontalinterval at which the pixel circuit 25 is written, and the gate terminalof the TFT: M21 is initialized by using the initialization voltage Vini.The gate voltage of the TFT: M21 after the initialization is(Vini+|VthC|). The source terminal of the TFT: M26 is connected to theanode terminal of the organic EL element L2, the drain terminal of theTFT: M26 is applied with the initialization voltage Vini, and the gateterminal of the TFT: M26 is connected to the scanning line Gi. Thus, theTFT: M26 is turned on in a horizontal interval at which the pixelcircuit 25 is written, and the anode terminal of the organic EL elementL2 is initialized by using the initialization voltage Vini. The anodevoltage of the organic EL element L2 after the initialization is Vini.In the display device 20, the gate terminal of the TFT: M21 isinitialized by turning on the TFTs: M25 and M27, the anode terminal ofthe organic EL element L2 is initialized by turning on the TFT: M26, andthe data voltage Vd according to the image signal VS is applied to thegate terminal of the TFT: M21 by driving the scanning line Gi and thedata line Sj. As a result, an image according to the image signal VS canbe displayed.

In the display device 20 according to the present embodiment, the gatevoltage of the drive transistor (TFT: M21) is initialized to(Vini+|VthC|), and the anode voltage of the organic EL element L2 isinitialized to Vini. In this way, the gate terminal of the drivetransistor and the anode terminal of the organic EL element L2 areinitialized to the different voltage levels. Thus, in a case where thethreshold voltage VthC of the TFT: M27 is appropriately determined, thegeneration of the bright spots can be prevented by increasing the gatevoltage of the TFT: M24 after the initialization, while the generationof the black floating can be prevented by lowering the anode voltage ofthe organic EL element L2 after the initialization.

As described above, according to the display device 20 according to thepresent embodiment, similar to the first embodiment, both the brightspots and the black floating can be suppressed by initializing the gateterminal of the drive transistor (TFT: M21) and the anode terminal ofthe electro-optical element (organic EL element L2) to the differentvoltage levels. The gate terminal of the drive transistor and the anodeterminal of the electro-optical element are initialized by using thesame wiring line (the wiring line applied with the initializationvoltage Vini), and this can prevent the layout area of the displayportion 21 from increasing.

Third Embodiment

A display device according to a third embodiment has the sameconfiguration as that of the display device according to the firstembodiment (refer to FIG. 1). The display device according to thepresent embodiment, however, includes a pixel circuit 35 illustrated inFIG. 10 instead of the pixel circuit 15. The pixel circuit 35illustrated in FIG. 10 is a pixel circuit in which a capacitor C3 isadded to the pixel circuit 15 according to the first embodiment. Thecapacitor C3 is provided between the source terminal and the gateterminal of the TFT: M14 and functions as a holding capacitor.

In general, in a case where a current flows through a power sourcewiring line having a resistance component, the power supply voltage islowered (IR drop). In the display device according to the presentembodiment, in a case where the high-level power supply voltage ELVDD islowered by the IR drop, the source voltage of the TFT: M14 is alsolowered. Since the source terminal and the gate terminal of the TFT: M14are connected to each other with the capacitor C3 therebetween, in acase where the source voltage of the TFT: M14 is lowered, the gatevoltage of the TFT: M14 is also lowered by the action of the capacitorC3. Thus, the effect of the IR drop on the first power source wiringline 16 can be mitigated.

In the display device according to the present embodiment, the pixelcircuit 35 includes a capacitor C3 provided between the first conductionterminal (the source terminal of the TFT: M14) and the gate terminal ofthe drive transistor. According to the display device according to thepresent embodiment, the effect of the IR drop on the first power sourcewiring line 16 can be mitigated.

As described above, the organic EL display device including the pixelcircuit including the organic EL element (organic light emitting diode)is described as an example of a display device including a pixel circuitincluding an electro-optical element, but an inorganic EL display deviceincluding a pixel circuit including an inorganic light emitting diodeand a Quantum-dot Light Emitting Diode (QLED) display device including apixel circuit including a QLED may be configured by a similar method.

REFERENCE SIGNS LIST

-   10, 20 Display device-   11, 21 Display portion-   12 Display control circuit-   13 Scanning line drive/light emission control circuit-   14 Data line drive circuit-   15, 25, 35 Pixel Circuit-   16 First power source wiring line-   17 Second power source wiring line-   23 Scanning line drive circuit

The invention claimed is:
 1. A display device, comprising: a displayportion including a plurality of scanning lines, a plurality of datalines, and a plurality of pixel circuits two-dimensionally arranged; ascanning line drive circuit configured to drive the plurality ofscanning lines; and a data line drive circuit configured to drive theplurality of data lines, wherein each of the plurality of pixel circuitsincludes an electro-optical element provided on a path connecting afirst conductive member and a second conductive member for supplying apower supply voltage and configured to emit light at brightnessaccording to a current flowing through the path, a drive transistorprovided in series with the electro-optical element on the path andconfigured to control the amount of current flowing through the path, afirst transistor including a first conduction terminal connected to ananode terminal of the electro-optical element, a second conductionterminal to which an initialization voltage is applied, and a gateterminal connected to a scanning line of the plurality of scanninglines, a second transistor including a first conduction terminalconnected to a gate terminal of the drive transistor and a gate terminalconnected to an immediately preceding scanning line selected in ahorizontal interval immediately before the scanning line is selected,and a third transistor being diode-connected, and including a drainterminal and a gate terminal to which the initialization voltage isapplied, and a source terminal connected to a second conduction terminalof the second transistor.
 2. The display device according to claim 1,wherein the display portion further includes a plurality of lightemission control lines, each of the plurality of pixel circuits furtherincludes a writing control transistor including a first conductionterminal connected to a data line of the plurality of data lines, asecond conduction terminal connected to a first conduction terminal ofthe drive transistor, and a gate terminal connected to the scanningline, a threshold value compensation transistor including a firstconduction terminal connected to a second conduction terminal of thedrive transistor, a second conduction terminal connected to the gateterminal of the drive transistor, and a gate terminal connected to thescanning line, a first light emission control transistor including afirst conduction terminal connected to the first conductive member, asecond conduction terminal connected to the first conduction terminal ofthe drive transistor, and a gate terminal connected to a light emissioncontrol line of the plurality of light emission control lines, a secondlight emission control transistor including a first conduction terminalconnected to the second conduction terminal of the drive transistor, asecond conduction terminal connected to the anode terminal of theelectro-optical element, and a gate terminal connected to the lightemission control line, and a capacitor provided between the firstconductive member and the gate terminal of the drive transistor, and theelectro-optical element includes a cathode terminal connected to thesecond conductive member.
 3. The display device according to claim 2,wherein each of the plurality of pixel circuits further includes acapacitor provided between the first conduction terminal and the gateterminal of the drive transistor.
 4. The display device according toclaim 2, wherein a gate voltage of the drive transistor afterinitialization is greater than an anode voltage of the electro-opticalelement after the initialization.
 5. The display device according toclaim 4, wherein the gate voltage of the drive transistor after theinitialization is equal to a voltage obtained by adding an absolutevalue of a threshold voltage of the third transistor to theinitialization voltage, and the anode voltage of the electro-opticalelement after the initialization is equal to the initialization voltage.6. The display device according to claim 1, wherein each of theplurality of pixel circuits further includes a writing controltransistor including a first conduction terminal connected to a dataline of the plurality of data lines and a gate terminal connected to thescanning line, a threshold value compensation transistor including afirst conduction terminal connected to a second conduction terminal ofthe writing control transistor, and a second conduction terminal and agate terminal connected to the gate terminal of the drive transistor, afourth transistor including a first conduction terminal connected to theanode terminal of the electro-optical element, a second conductionterminal connected to a second conduction terminal of the drivetransistor, and being complementarily conducted to the secondtransistor, and a capacitor provided between the first conductive memberand the gate terminal of the drive transistor, the drive transistorincludes a first conduction terminal connected to the first conductivemember, and the electro-optical element includes a cathode terminalconnected to the second conductive member.
 7. The display deviceaccording to claim 1, wherein the second transistor and the thirdtransistor are turned on in a case where a low-level voltage is appliedto the gate terminal of the second transistor, and the gate terminal ofthe drive transistor is initialized by using the initialization voltage.8. The display device according to claim 7, wherein the third transistoris a P-channel transistor.
 9. The display device according to claim 8,wherein Relationship (a) below is satisfied, where the initializationvoltage is Vini, a voltage of the second conductive member is ELVSS, amaximum value of the amount of variation of the anode voltage of theelectro-optical element in a non-light emission period of theelectro-optical element is ΔV, and a light emission threshold voltage ofthe electro-optical element is Vem,Vini−ELVSS+ΔV<Vem  (a).
 10. The display device according to claim 1,wherein the electro-optical element is any one of an organic lightemitting diode, an inorganic light emitting diode, or a quantum dotlight emitting diode.
 11. A method for driving a display deviceincluding a display portion including a plurality of scanning lines, aplurality of data lines, and a plurality of pixel circuitstwo-dimensionally arranged, the method comprising: in a case where eachof the plurality of pixel circuits includes an electro-optical elementprovided on a path connecting a first conductive member and a secondconductive member for supplying a power supply voltage and configured toemit light at brightness according to a current flowing through thepath, a drive transistor provided in series with the electro-opticalelement on the path and configured to control the amount of currentflowing through the path, a first transistor including a firstconduction terminal connected to an anode terminal of theelectro-optical element, a second conduction terminal to which aninitialization voltage is applied, and a gate terminal connected to ascanning line of the plurality of scanning lines, a second transistorincluding a first conduction terminal connected to a gate terminal ofthe drive transistor and a gate terminal connected to an immediatelypreceding scanning line selected in a horizontal interval immediatelybefore the scanning line is selected, and a third transistor beingdiode-connected, and including a drain terminal and a gate terminal towhich the initialization voltage is applied, and a source terminalconnected to a second conduction terminal of the second transistor,initializing the gate terminal of the drive transistor by turning on thesecond and third transistors; initializing the anode terminal of theelectro-optical element by turning on the first transistor; and applyinga voltage according to an image signal to the gate terminal of the drivetransistor by driving the scanning line and a data line of the pluralityof the data lines.
 12. The method for driving a display device accordingto claim 11, wherein the display portion further includes a plurality oflight emission control lines, each of the plurality of pixel circuitsfurther includes a writing control transistor including a firstconduction terminal connected to the data line, a second conductionterminal connected to a first conduction terminal of the drivetransistor, and a gate terminal connected to the scanning line, athreshold value compensation transistor including a first conductionterminal connected to a second conduction terminal of the drivetransistor, a second conduction terminal connected to the gate terminalof the drive transistor, and a gate terminal connected to the scanningline, a first light emission control transistor including a firstconduction terminal connected to the first conductive member, a secondconduction terminal connected to the first conduction terminal of thedrive transistor, and a gate terminal connected to a light emissioncontrol line of the plurality of light emission control lines, a secondlight emission control transistor including a first conduction terminalconnected to the second conduction terminal of the drive transistor, asecond conduction terminal connected to the anode terminal of theelectro-optical element, and a gate terminal connected to the lightemission control line, and a capacitor provided between the firstconductive member and the gate terminal of the drive transistor, and theelectro-optical element includes a cathode terminal connected to thesecond conductive member, the initializing of the gate terminal of thedrive transistor is performed in a horizontal interval immediatelybefore a horizontal interval at which the plurality of pixel circuitsare written, and the initializing of the anode terminal of theelectro-optical element is performed in a horizontal interval at whichthe plurality of pixel circuits are written.
 13. The method for drivinga display device according to claim 12, wherein each of the plurality ofpixel circuits further includes a capacitor provided between the firstconduction terminal and the gate terminal of the drive transistor. 14.The method for driving a display device according to claim 12, wherein agate voltage of the drive transistor after initialization is greaterthan an anode voltage of the electro-optical element after theinitialization.
 15. The method for driving a display device according toclaim 14, wherein the gate voltage of the drive transistor after theinitialization is equal to a voltage obtained by adding an absolutevalue of a threshold voltage of the third transistor to theinitialization voltage, and the anode voltage of the electro-opticalelement after the initialization is equal to the initialization voltage.16. The method for driving a display device according to claim 11,wherein each of the plurality of pixel circuits further includes, awriting control transistor including a first conduction terminalconnected to the data line and a gate terminal connected to the scanningline, a threshold value compensation transistor including a firstconduction terminal connected to a second conduction terminal of thewriting control transistor and a second conduction terminal and a gateterminal connected to the gate terminal of the drive transistor, afourth transistor including a first conduction terminal connected to theanode terminal of the electro-optical element, a second conductionterminal connected to a second conduction terminal of the drivetransistor, and being complementarily conducted to the secondtransistor, and a capacitor provided between the first conductive memberand the gate terminal of the drive transistor, the drive transistorincludes a first conduction terminal connected to the first conductivemember, the electro-optical element includes a cathode terminalconnected to the second conductive member, the initializing of the gateterminal of the drive transistor is performed in a horizontal intervalimmediately before a horizontal interval at which the plurality of pixelcircuits are written; and the initializing of the anode terminal of theelectro-optical element is performed in the horizontal interval at whichthe plurality of pixel circuits are written.
 17. The method for drivinga display device according to claim 11, wherein the second and thirdtransistors are turned on in a case where a low-level voltage is appliedto the gate terminal of the second transistor, and the gate terminal ofthe drive transistor is initialized by using the initialization voltage.18. The method for driving a display device according to claim 17,wherein the third transistor is a P-channel transistor.
 19. The methodfor driving a display device according to claim 18, wherein Relationship(b) below is satisfied, where the initialization voltage is Vini, avoltage of the second conductive member is ELVSS, a maximum value of theamount of variation of an anode voltage of the electro-optical elementin a non-light emission period of the electro-optical element is ΔV, andthe light emission threshold voltage of the electro-optical element isVem,Vini−ELVSS+ΔV<Vem  (b).
 20. The method for driving a display deviceaccording to claim 11, wherein the electro-optical element is any one ofan organic light emitting diode, an inorganic light emitting diode, or aquantum dot light emitting diode.